Consistency of rulings is not a strong point of UCI and it seems that these types of decisions are left to personal interpretation of the officials on the day rather than a simple written ruling which is enforceable in all situations! Iceman is correct, it does not matter whether there is an advantage or not when exiting the race track line denoted by boundary tape - the rider must return to the point of exit from the track and rejoin the race at that point! Pretty simple I think?